1. Field of the Invention
The invention relates to voltage measuring apparatus for use with high-voltage circuits, such as high-voltage electric power transmissions systems and, in particular, to the testing of such measuring apparatus.
2. Description of the Prior Art
In high-voltage electrical systems, such as electrical transmission lines and equipment, it is frequently necessary to determine if selected lines or wires are energized and/or to measure the voltage between two points in the system, such as the voltage between two transmission lines or wires or the voltage between a single wire and ground. Because of the high voltage involved, it is essential that test personnel be able to safely connect the test equipment to the high voltage lines. For this purpose, elongated, insulated sticks or poles are used to permit personnel to contact electrically energized circuits.
One common type of test equipment is a voltmeter which includes two probes adapted to be electrically coupled to the two points in the high-voltage circuit between which electric potential is to be measured, and a meter connected between the two probes. In one form of this type of voltmeter, both of the probes are mounted at the ends of elongated insulated sticks or poles, and in another form one of the probes is on an insulated pole and the other probe may be at the end of a ground cable.
It is desirable to be able to test the operation of such voltmeters to determine electrical continuity within the voltmeter, to check the operability and calibration of the meter and to determine proper connection between the probes. Indeed, certain government regulations now require high voltage testing of such voltmeters before and after each use. Heretofore, this has been a significant inconvenience since high-voltage sources are not readily available. Accordingly, a crew typically has to be dispatched to a remote location where a known voltage source is available in order to confirm proper operation of the voltmeter.